Once two separate municipalities (one a city and the other a town) both named Las Vegas, west Las Vegas (“Old Town”) and east Las Vegas (“New Town”), separated by the Gallinas River, retain distinct characters and separate, rival school districts. The population was 14,565 at the 2000 census. Las Vegas, NM is located 110 miles (180 km) south of Raton, New Mexico, 65 miles (105 km) east of Santa Fe, New Mexico, 122 miles (196 km) northeast of Albuquerque, New Mexico, 257 miles (414 km) south of Colorado Springs, Colorado, and 326 miles (525 km) south of Denver, Colorado.
Las Vegas was established in 1835 after a group of settlers received a land grant from the Mexican government. The town was laid out in the traditional Spanish Colonial style, with a central plaza surrounded by buildings which could serve as fortifications in case of attack. Las Vegas soon prospered as a stop on the Santa Fe Trail. During the Mexican-American War in 1846,Stephen W. Kearny delivered an address at the Plaza of Las Vegas claiming New Mexico for the United States. In 1877 Las Vegas College, the precursor to Regis University, was founded in Las Vegas by a group of exiled Italian Jesuits. In 1887, Las Vegas College moved to Denver whereupon the name was changed.
A railroad was constructed to the town in 1880. To maintain control of development rights, it established a station and related development one mile (1.6 km) east of the Plaza, creating a separate, rival New Town (as occurred elsewhere in the Old West. The same competing development occurred in Albuquerque, for instance). During the railroad era Las Vegas boomed, quickly becoming one of the largest cities in the American Southwest. Turn-of-the-century Las Vegas featured all the modern amenities, including an electric street railway, the “Duncan Opera House” at the northeast corner of 6th Street and Douglas Avenue, a Carnegie library, the Hotel Castaneda (a major Harvey House), and the New Mexico Normal School (now New Mexico Highlands University). Since the decline and restructuring of the railroad industry began in the 1950s, the city’s population has remained relatively constant. Although the two towns have been combined, separate school districts have been maintained (Las Vegas City Schools and West Las Vegas School District).
The anti-colonist organization Las Gorras Blancas was active in the area in the 1890s.
The first billed Cowboy Reunions were held once a year within 1915 until 1931. These reunions were meant to celebrate the ranching life that took place in northern New Mexico in the late 1800’s. These reunions consisted of fair like activities, including pie eating contests, barbecues, and parades. They brought the working cowhand and celebrities of Rodeos together in the town of Las Vegas. The Cowboy Reunions reflected the occupations of the area. 
The arrival of the railroad on July 4, 1879 brought with it businesses, development and new residents, both respectable and dubious. Murderers, robbers, thieves, gamblers, gunmen, swindlers, vagrants, and tramps poured in, transforming the eastern side of the settlement into a virtually lawless brawl. Among the notorious characters were such legends of the Old West as: dentist Doc Holliday and his girlfriend Big Nose Kate, Jesse James, Billy the Kid,Wyatt Earp, Mysterious Dave Mather, Hoodoo Brown, and Handsome Harry the Dancehall Rustler.